import mimeMap from './mimeMap'

type File = {
  name: string
  buffer: ArrayBuffer | string
  fileName: string
}

class FormData {
  fileManager = uni.getFileSystemManager()
  data: { [key: string]: any } = {}
  files: File[] = []

  append(name: string, value: string) {
    this.data[name] = value
    return true
  }

  appendFile(name: string, path: string, fileName: string) {
    const buffer = this.fileManager.readFileSync(path)

    if (Object.prototype.toString.call(buffer).indexOf('ArrayBuffer') < 0) {
      return false
    }

    if (!fileName) {
      fileName = getFileNameFromPath(path)
    }

    this.files.push({
      name,
      buffer,
      fileName,
    })
    return true
  }

  getData() {
    return convert(this.data, this.files)
  }
}

function getFileNameFromPath(path: string) {
  let idx = path.lastIndexOf('/')
  return path.slice(idx + 1)
}

function convert(data: { [key: string]: any }, files: File[]) {
  let boundaryKey = 'wxmpFormBoundary' + randString() // 数据分割符，一般是随机的字符串
  let boundary = '--' + boundaryKey
  let endBoundary = boundary + '--'

  let postArray: any[] = []

  //拼接参数
  if (data && Object.prototype.toString.call(data) == '[object Object]') {
    for (let key in data) {
      postArray = postArray.concat(formDataArray(boundary, key, data[key]))
    }
  }

  //拼接文件
  if (files && Object.prototype.toString.call(files) == '[object Array]') {
    for (let i in files) {
      let file = files[i]
      postArray = postArray.concat(formDataArray(boundary, file.name, file.buffer, file.fileName))
    }
  }
  //结尾
  let endBoundaryArray = []
  endBoundaryArray.push(...toUtf8Bytes(endBoundary))
  postArray = postArray.concat(endBoundaryArray)
  return {
    contentType: 'multipart/form-data; boundary=' + boundaryKey,
    buffer: new Uint8Array(postArray).buffer,
  }
}

function randString() {
  var result = ''
  var chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
  for (var i = 17; i > 0; --i) result += chars[Math.floor(Math.random() * chars.length)]
  return result
}

function formDataArray(boundary: string, name: string, value: any, fileName?: string) {
  let dataString = ''
  let isFile = !!fileName

  dataString += boundary + '\r\n'
  dataString += 'Content-Disposition: form-data; name="' + name + '"'

  if (isFile) {
    dataString += '; filename="' + fileName + '"' + '\r\n'
    dataString += 'Content-Type: ' + getFileMime(fileName!) + '\r\n\r\n'
  } else {
    dataString += '\r\n\r\n'
    dataString += value
  }

  var dataArray = []
  dataArray.push(...toUtf8Bytes(dataString))

  if (isFile) {
    let fileArray = new Uint8Array(value)
    dataArray = dataArray.concat(Array.prototype.slice.call(fileArray))
  }
  dataArray.push(...toUtf8Bytes('\r'))
  dataArray.push(...toUtf8Bytes('\n'))

  return dataArray
}

function getFileMime(fileName: string) {
  const idx = fileName.lastIndexOf('.')
  const mime = mimeMap[fileName.slice(idx)]

  return mime || 'application/octet-stream'
}

function toUtf8Bytes(str: string) {
  var bytes = []
  for (var i = 0; i < str.length; i++) {
    bytes.push(...utf8CodeAt(str, i))

    if (str.codePointAt(i)! > 0xffff) i++
  }
  return bytes
}

function utf8CodeAt(str: string, i: number) {
  const out = []
  let p = 0
  let c = str.charCodeAt(i)
  if (c < 128) {
    out[p++] = c
  } else if (c < 2048) {
    out[p++] = (c >> 6) | 192
    out[p++] = (c & 63) | 128
  } else if (
    (c & 0xfc00) == 0xd800 &&
    i + 1 < str.length &&
    (str.charCodeAt(i + 1) & 0xfc00) == 0xdc00
  ) {
    // Surrogate Pair
    c = 0x10000 + ((c & 0x03ff) << 10) + (str.charCodeAt(++i) & 0x03ff)
    out[p++] = (c >> 18) | 240
    out[p++] = ((c >> 12) & 63) | 128
    out[p++] = ((c >> 6) & 63) | 128
    out[p++] = (c & 63) | 128
  } else {
    out[p++] = (c >> 12) | 224
    out[p++] = ((c >> 6) & 63) | 128
    out[p++] = (c & 63) | 128
  }
  return out
}

export { FormData }
